At 30kg - +/-3.5g
see below

I was suspicious of my cell with its 2kg load - a pretty good accelerometer - so plugged in the simulator and got:
At 30kg - +/-0.4g
Go out and sell your scale stating "it works great in the simulator, what you get is not that good"

These are excellent results for such an ADC - ~+/-1/100,000
Who gives a hoot what happens in a simulator. 30 kg to 3.5g is NOT 1:100,000 it is ~1:8,000. that still is way better than one would expect. Now did you check zero drift? did you check span drift? did you check lineraity?, did yoy check temperature drift? did you check EMI?.

I can make a scale work perfectly for a minute and the same sacle would not pass weights and measures.

Erik